**Today, most of us find it commonsensical to think that our minds are tucked away in our bodies, hidden from others, while the skin provides a boundary of our precious selves. But this is not the only way to think about ourselves. What if thoughts and feelings float in bundles, passing from one to another, transmitted like viruses through physical media?

The Topic: Do Minds Depend on Other Minds?

Traditionally, philosophers of mind seem to be mainly interested in the question of how the mind relates to the world or what it means for a mind to cognise an object. So one might ask what happens if a mind recognises a thing that we call a tree. By contrast, I am interested in the question of how a mind relates to other minds. So one might ask whether minds depend on other minds. The idea is that it is not sufficient to explain mental states by looking at an individual mind. Rather, we ought to recognise that the way minds interact might play a crucial role for the way mental states are shaped. Thus, I’m interested in countering individualistic approaches to the mind with intersubjective explanations.

How, then, do our minds depend on other minds? There are a number of well-known phenomena that might serve as illustrations. Our lives and mental lives in particular are to a great extent determined by education, biases and ideologies; much of our knowledge relies on the testimony of others; our beliefs can be strengthened by the authority of others; our emotions might change in the presence of friends; our inclination to act can be triggered by the courage of others; our thoughts might be completed by the perspective of others. Such influence on individual minds might be more or less explicit, but cannot be explained without appealing to the thoughts and sentiments that others have.

The Contact Problem

But there seems to be an obvious problem: how can minds interact? How, for instance, does it happen that we might share attitudes and views without explicitly talking about them? Many approaches to the mind do not seem to allow for such explanations in the first place. Especially explanations inherited from early modern approaches seem to construe the mind as something that is tucked away in a body and thus inaccessible by other minds. If this is correct, how could we even begin to think of a way in which my thoughts influence yours? Are there ways of transmission or other modes of influence between different minds? I call this the contact problem. Intersubjective explanations, it seems, must specify ways in which one mind can affect another mind.

A Historical Hypothesis

Now, if you are interested in this issue, philosophers and historians of philosophy will instruct you to read up on some classics such as Husserl, Wittgenstein and Ryle, and then steer you towards more contemporary practitioners such as Tomasello and Kiverstein. According to the canonical advice, the answer to the contact problem has two parts. First, you must overcome the individualistic concept of mind that we inherited from early modern philosophers such as Descartes or Hume. Secondly, wanting to tackle the contact problem, you should embrace a concept of mind that locates mental states not in some “ghost in the machine”, but in our behaviour and interaction.

While I am very sympathetic to the second part, I became increasingly doubtful about the first part of the advice. So much agreement about the past, especially among philosophers, is suspicious. Must we really overcome the early modern concept of mind to make progress? Despite being a diligent reader of early modern texts, I failed to find the individualism so often attributed to them. What I found instead was a number of approaches actually engaging with the contact problem. Reconsidering the concept of mind would thus involve reconsidering the way we are trained to think about (past philosophies of) the mind. Especially the supposed incompatibility of early modern concepts of mind with intersubjective approaches does not seem to hold. My hunch was that a careful reconsideration of canonical authors might confront us with a concept of mind that is quite different from the one attacked by Wittgenstein, Ryle and others. Spelling out my idea in detail left me with the core assumption that at least some early modern views are more than just compatible with an intersubjective approach to the mind.

Questions and Conclusions

In the light of this assumption, two questions arise: (1) Why and how did early modern philosophers develop intersubjective accounts of the mind? (2) Why do we – along with our Wittgensteinian ancestors – still assume that early modern philosophers are individualists? Let’s take these questions in turn.  

(Ad 1) So why were early modern philosophers bothered by the question of how minds exert influence on one another? Although it’s difficult to give one single motivation for all of them, a common core is the recognition that humans are superstitious and prone to hold all sorts of erroneous beliefs. The fact that we have such inclinations needs explanation. A common ingredient of such explanations is that we follow conventions. Remember that even Descartes, notoriously cited as an individualist about the mind, does not begin his Meditations with the cogito, but with the deconstruction of beliefs inherited from tradition. Generally speaking, most early modern philosophers were convinced that our minds are cluttered with thoughts that are not our own but rather echoes of conventions. But the acknowledgement that our minds are influenced by other minds does not per se entail any particular explanation of that fact. So how can minds influence one another? Looking at early modern texts, I identified three different models of intersubjectivity:

• Spinoza’s metaphysical model, according to which minds are shaped by their interaction;
• Locke’s linguistic model, according to which human minds develop through learning language which, in turn, is socially determined;
• Hume’s medical model, according to which human minds develop in accordance with shared physiological dispositions that mediate mentalities and views.

While the details of these approaches require quite some explanation, the upshot is that these authors were well aware of the interdependence of minds and the need to explain the mechanisms that are involved in the interaction of minds. So how do these models provide an answer to the contact problem? The linguistic model seems to provide the most obvious answer. In learning language, our minds pick up conventional ways of carving up categories of things. Spinoza’s metaphysical model, by contrast, is the most radical. Understanding what a human mind is means to understand it in relation to other minds, because minds are shaped by their power that, in turn, is determined by the degree of agreement or disagreement with others. Although Hume’s discussion of sympathy is well recognised as the introduction of an intersubjective take, the model behind this notion is difficult to trace. I think it is best understood as grounded in the medical understanding of the way bodies and, in turn, minds can be affected by other bodies via imagination. All of these models are aimed at explaining how minds might interact and how the thoughts of others might invade what we call our own minds, unbeknownst to ourselves. The emerging views are striking as they challenge (rather than propose) the idea that minds are containers of thoughts under the control of the individual thinker.

(Ad 2) Studying these theories, I often questioned my own findings. These are canonical authors. Could it really be true that these authors endorsed those models, while they are continuously read as individualists by so many of my peers? It is crucial, then, to see that it’s not enough to challenge the canon by extending it. We also have to challenge canonical readings of “well known” authors. This cannot be a simple question of one line of interpretation being right, while all the others are wrong. If we think that others are misguided, we need an explanation of how this misguidance might arise. I offer two reasons. Firstly, I began to realise that individualist assumptions about minds as well as the reactions against them might be a matter arising in the 19th and 20th centuries. A telling point is that the so-called problem of other minds does not really arise for early modern authors. As Anita Avramides (Oxford) has shown, the problem is a fairly late invention and depends on particular ways of thinking about minds. So if we find individualist concepts of mind in past philosophies, we should keep track of our projections that might be guided to a greater extent by our contemporary lenses rather than by the original texts. Secondly, we have to recognise that a lot of our intellectual history is indeed still unknown. Especially recent work in medieval and early modern natural philosophy suggests an understanding of body and mind that is quite remote from any form of individualism. It took me many conversations – especially with Evelina Miteva (Cologne), Doina Rusu (Groningen) and Charles Wolfe (Ghent) – to finally see that there are whole traditions yet to be uncovered. According to many medieval and early modern positions, minds might be seen as acting upon one another, just as bodies can be contagious. So when we read Hume speaking of the “contagion of opinion”, for instance, he is obviously appealing to a model that goes back a long way. Mental states might spread like diseases and enter us without our taking notice. Although we might not want to buy into all of the presuppositions these theories carry with them, they are well worth studying. They present us with unduly ignored alternatives to our current understanding of the mind. Far from suggesting that we are autonomous individuals, these theories seem to support a view of ourselves as shaped by transient bundles of thoughts, perhaps to be seen in analogy of being affected by memes that spread through various media channels.

*This is also the title of the book that I am currently finalising.

** This piece appeared in March 2018 in the print edition of Qualia